1. Field of the Invention
The present invention relates generally to a portable terminal, and more particularly, to a touch screen device for a portable terminal.
2. Description of the Related Art
In general, portable terminals such as mobile communication terminals and portable multimedia devices typically include a display device and a transparent window member mounted on the display device.
A portable terminal allows its user to input information or perform various manipulations using a separate input device such a keypad and a trackpad. Recently, however, as users may perform various functions such as Internet access and multimedia playback even on a mobile communication terminal, a touch screen is implemented on the display devices of portable terminals. That is, display devices having a sufficient size are mounted for Internet access and multimedia features, and instead of separate input devices, a touch screen feature incorporated on the display device serves as both input and output devices. Currently, the growing trend is that portable terminals are becoming thinner and smaller while the display area of a screen is getting larger to enhance the user's experience.
Despite implementing a touch screen feature, the most frequently used main function keys, for example, a Menu key (menu call key), a Back key (command key for turning back to the previous screen), and a Home key (command key for switching to the main screen), are generally provided at the bottom of the touch screen.
FIGS. 1 to 5 are diagrams showing the conventional touch screen device 10 with a structure in which the above-mentioned main function keys are disposed adjacent to each other in an area 11. The touch screen device 10 has a bezel that is formed on an inner surface of a window member 17 by conducting coating, and a logo of a carrier or a manufacturer may be printed in an area where the bezel is formed. A keypad area 13 is typically provided at one side of the area 11 and includes the frequently used main function keys such as a Menu key, a Back key and a Home key in the keypad area 13.
Referring to FIGS. 3 and 4, an Indium Tin Oxide (ITO) film 15, known as a touchpad, is attached onto the window member 17, and a substrate assembly 20 for providing lighting to the keypad area 13 is provided thereunder. The substrate assembly 20 includes a printed circuit board 21 on which light emitting devices 23 are disposed in their associated places corresponding to the keys disposed in the keypad area 13, and the substrate assembly 20 is installed to be accommodated between upper and lower cases 31 and 33 of the portable terminal.
The substrate assembly 20 has a thickness similar to or greater than that of the display device, thus making it difficult to ensure its installation space during the fabrication process. Further, such a cumbersome assembly has a drawback in efforts to miniaturize the portable terminal. Moreover, a separate manufacturing process for assembling and installing the substrate assembly 20 is required which in turn raises the manufacturing cost.
Further, referring to FIG. 5, when a pair of housings is coupled to each other in a slide manner, a space 35 for coupling slide rails should be secured on the face facing in the screen display direction. However, the substrate assembly 20 having a thickness similar to or greater than that of the display device is an obstacle in securing the space 35 for coupling slide rails. When the display device, the slide rail coupling space, and the substrate assembly are placed on the same plane due to the limited thickness of the portable terminal, there are many limitations, therefore, in expanding the display device and setting the position of the substrate assembly.